I got them working,
It looks like its the Synaptics touch pad driver that makes them work. Looks like I came to the right place for an answer too. > Acer Aspire 5920g
I had downloaded the Acer recommended driver for my 5920, v14 I think, but it wouldn't install. I just downloaded the Aspire 5738 driver (v13 something) and it installed OK. I know have an Acer Media Touch tab that enables those blue keys.
When the Acer driver wouldn't install I went right to Synaptics for the latest driver. It worked but didn't work with the media keys, the Acer one must be customized. Maybe the middle scroll button will work correctly now too.
EDIT:As a bonus my touch pad middle scroll button works as advertised. I was also able to reprogram the scroll up function to page back. =)